How do Logical Operators Work in JavaScript?

Understanding Logical Operators in JavaScript

In JavaScript, logical operators are essential for evaluating and combining conditional statements. The three primary logical operators—&& (AND), || (OR), and ! (NOT)—behave differently depending on the type of data they're applied to.

AND (&&)

The AND operator returns the first falsy operand or the last operand if all are truthy. Truthiness and falsiness in JavaScript are based on predefined values: falsy values include null, undefined, false, 0, -0, NaN, empty strings, and document.all, while all other values are truthy.

OR (||)

The OR operator returns the first truthy operand or the last operand if all are falsy. Like the AND operator, it considers the truthiness of operands and returns the first non-falsy value if it exists.

NOT (!)

The NOT operator inverts the truthiness of its operand. If the operand is truthy, ! will return false; if the operand is falsy, ! will return true.

Examples:

• true && false → false
• true && true → true
• false || true → true
• false || false → false
• !true → false
• !false → true

By understanding the behavior of these logical operators, you can effectively combine conditions in your JavaScript code and create more accurate and efficient conditional logic.

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